Gasket for sealing a refrigerant compressor

ABSTRACT

A metallic base gasket coated with elastic membrane having an outer sealing portion for sealing an outer circumference of a refrigerant compressor and an inner sealing portion for sealing boundaries between high and low pressure regions within the compressor, the outer and inner sealing portions being formed in an elastically deformable ridge, and at least one section of the ridge of the inner sealing portion being trifurcatedly connected to a portion of the ridge of the outer sealing portion to have a geometrical arrangement in which apex lines of the connected three ridges are equiangularly spaced apart from one another with respect to the center of the trifurcated connection of the ridges. The gasket may have an extended flat or curved face portion at the trifurcatedly connected ridges to permit the apexes of the connected ridges lie in the extended flat or curved face portion.

This is a continuation of application Ser. No: 08/988,078 filed: Dec.10. 1997 by Hayto IKEDA. et al for GASKET FOR SEALING A REFRIGERANTCOMPRESSOR, now U.S. Pat. No. 6,068,265.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a gasket for sealing arefrigerant compressor and, more particularly, relates to a metallicgasket covered with an elastic coating and adapted for providing aconnecting portion between a cylinder block and end housings of arefrigerant compressor, and between high and low pressure regions insidethe compressor, with a stable fluid-tight seal.

2. Description of the Related Art

In conventional refrigerant compressors such as swash plate and wobbleplate type refrigerant compressors, a pair of front and rear cylinderblocks are axially combined together to define, at a connecting portionof both cylinder blocks, a swash plate chamber in which a refrigerantreturning from an external refrigerating system is introduced to becompressed. The opposite ends of the combined front and rear cylinderblocks are closed by front and rear housings via front and rear valveplates and associated discharge valves. Each of the front and rearhousings is provided with a radially outer suction chamber for therefrigerant gas before compression and a radially inner dischargechamber for the compressed refrigerant gas. The combined front and rearcylinder blocks are provided with a common central shaft bore forreceiving therein an axial drive shaft on which a swash plate is fixedlymounted so as to be rotated with the drive shaft within the swash platechamber. The combined front and rear cylinder blocks are provided with aplurality of axially extending cylinder bores in which double headedpistons operatively engaged with the swash plate via shoes are receivedto be reciprocated to implement suction and compression of therefrigerant gas, and to discharge the compressed refrigerant gas. Eachof the front and rear valve plates is provided with suction ports boredtherein and fluidly connected to the associated front or rear suctionchamber. The suction ports of the front and rear valve plates areopenably closed by suction valves. The front and rear valve plates arealso provided with a plurality of discharge ports which are fluidlyconnected to the front and rear discharge chambers via the openabledischarge valves and valve retainers which are formed as one part withgasket members interposed between the respective valve plates and thefront and rear housings. The discharge ports of the front and rear valveplates are arranged to be in registration with the cylinder bores of thefront and rear cylinder blocks to discharge the compressed refrigerantgas toward the front and rear discharge chambers through the dischargevalves. The front and rear suction chambers and the swash plate chamberare in fluid communication by suction passageways formed in the combinedcylinder blocks. Similarly, the front and rear discharge chambers are influid communication by discharge passageways formed in the combinedcylinder blocks.

The outer framework of the refrigerant compressor provided by theabove-mentioned combined front and rear cylinder blocks and the frontand rear housings must be completely sealed against the atmosphericenvironment therearound. Further, since the compressor has, in theinterior thereof, a low pressure region in which a suction pressureprevails, and a high pressure region in which a high pressuresubstantially corresponding to the compressed gas pressure prevails, thehigh and low pressure regions within the compressor must also beappropriately isolated from one another. Thus, gaskets have beensuitably incorporated in the compressor.

One of the typical gaskets assembled in a generally cylindrical body ofa conventional refrigerant compressor is shown in FIGS. 6 and 7. Namely,a gasket 50 according to the prior art is made of a metallic platecoated with a thin elastic membrane. As best shown in FIG. 6, the gasket50 includes an outer sealing portion 51 in the shape of a circular rim,and an inner sealing portion 52 in the shape of an annular rim arrangedinside the outer sealing portion 51 and having curved portions extendingtoward and connected to the outer sealing portion 51. The outer sealingportion 51 functions to seal a circumferential region of the outerframework of the compressor against the atmosphere, and the innersealing portion 52 functions to seal boundaries between the highpressure regions designated by “a” and the low pressure regionsdesignated by “b”, within the compressor body.

The gasket 50 further includes five radial ribs 53 between a centralbase rim 54 and the annular inner sealing portion 52 to function asvalve retainers for determining an amount of opening of the dischargevalves.

The gasket 50 has a ridge 61 arranged in the circular outer sealingportions 51 and a ridge 62 arranged in the annular inner sealing portion52. These ridges 61 and 62 of the outer and inner sealing portions 51and 52 of the gasket 50 are occasionally referred to as “beads”, and areformed as smoothly curved projections having a continuously runningapex, respectively (the apexes of the ridges 61 and 62 are shown bysolid lines in FIG. 6, and these lines will be referred to as “an apexline” throughout the description hereinafter). The ridges 61 and 62 aretrifurcatedly connected to one another at portions “A” and “B” where theouter sealing portion 51 and the inner sealing portion 52 are connectedto each other. An enlarged view of the connecting portion “A” is shownin FIG. 7. The trifurcated connection of the ridges 61 and 62 of theouter and inner sealing portions 51 and 52 is achieved by a normalT-shape connection at the portion “A”, and by an irregular T-shapeconnection at the portion “B”. Nevertheless, the above-mentioned twotrifurcated connections of the ridges 61 and 62 of the outer and innersealing portions 51 and 52 have defects as set forth below. Namely, whenthe ridges 61 and 62 of the outer and inner sealing portions 51 and 52of the gasket 50 are compressed between by two mated parts such as anend of the front or rear cylinder block and the front or rear housing tobe elastically deformed and collapsed, the mechanical rigidity ofspecified sections of the ridges 61 and 62, which are arranged adjacentto the connecting portions “A” and “B”, is increased in comparison withthe remaining sections of the ridges 61 and 62, and accordingly, theridges 61 and 62 of the outer and inner sealing portions 51 and 52 ofthe gasket 50 cannot be elastically deformed uniformly which results ina failure to exhibit a stable sealing function at the connectingportions “A” and “B”.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide a metallicbase gasket for refrigerant compressors which is improved so as toobviate the defects encountered by the conventional gasket forrefrigerant compressors.

Another object of the present invention is to provide a metallic gasket,with a thin elastic membrane coating, adapted for use with refrigerantcompressors which exhibits a stable and good sealing function in everysection of the sealing portions thereof.

In accordance with one aspect of the present invention, there isprovided a gasket having a surface thereof coated with an elasticmembrane, adapted to being interposed, together with a valve plate and adischarge valve, between a cylinder block and a housing of a refrigerantcompressor under compression, comprising:

an outer sealing portion for sealing an outer circumference of thecompressor against an atmospheric environment therearound;

an inner sealing portion for sealing between a high pressure region anda low pressure region within the compressor, the inner sealing portionbeing provided with at least one predetermined section thereoftrifurcatedly connected to the outer sealing portion; and

a deformable ridge portion formed in each of the outer and inner sealingportions to have the shape of a curved projection with a continuouslyextending apex line, the ridge of the predetermined section of the innersealing portion being interconnected with the ridge of the outer sealingportion to form a trifurcated connection in which three separate angles“θ” formed between three neighboring apex lines of the connected ridgesare made substantially equal to one another.

Since the trifurcatedly interconnected deformable ridge portions of theinner and outer sealing portions of the gasket form three equal anglesbetween the respective neighboring apex lines thereof, a balancedgeometrical arrangement of the deformable ridge portions of the innerand outer sealing portions can be obtained so as to exhibit asubstantially equal mechanical rigidity when the gasket is subjected toa compression between two mechanical parts, i.e., the cylinder block andthe housing of the refrigerant compressor. As a result, the deformableridge portions of the outer and inner sealing portions are elasticallydeformed so as to provide a stable and good sealing for not only theouter circumference of the compressor but also a boundary between thelow and high pressure regions within the compressor.

In accordance with another aspect of the present invention, there isprovided a gasket having a surface thereof coated with an elasticmembrane, adapted to being interposed, together with a valve plate and adischarge valve, between a cylinder block and a housing of a refrigerantcompressor under compression, comprising:

an outer sealing portion for sealing an outer circumference of thecompressor against an atmospheric environment therearound;

an inner sealing portion for sealing between a high pressure region anda low pressure region within the compressor, the inner sealing portionbeing provided with at least one predetermined section thereoftrifurcatedly connected to the outer sealing portion; and

a deformable ridge portion formed in each of the outer and inner sealingportions to have the shape of a curved projection with a continuouslyextending apex line, the ridge portion of the predetermined section ofthe inner sealing portion being connected to the ridge portion of theouter sealing portion to form a trifurcated connection in which anextended and smooth face is provided to contain therein the apex linesof the connected ridge portions of the outer and inner sealing portions.

The extended and smooth face of the trifurcatedly connected ridgeportions of the outer and inner sealing portions of the gasket can comeinto face-to-face contact with two separate parts of the compressorbetween which the gasket is held under compression. Therefore, themechanical rigidities of the trifurcatedly connected respective ridgeportions of the outer and inner sealing portions can be madesubstantially equal within the above-mentioned extended and smooth face.Thus, the sealing function of the gasket exhibited by the trifurcatedlyconnected ridge portions of the outer and inner sealing portions can bevery stable and good. Further, the provision of the extended and smoothface at the trifurcated connection of the outer and inner sealingportions of the gasket can reduce abrasion of a die by which a metallicbase of the gasket before being coated with the elastic membrane isproduced by using a press machine. This is because the internal face ofthe die does not need to have a shaping portion to produce a trifurcatedconnection of apex lines of the ridge portions of the gasket. As theresult, a productivity of the gaskets by the die can be appreciablyincreased.

In accordance with a further aspect of the present invention, there isprovided a gasket having a surface thereof coated with an elasticmembrane and adapted to being interposed, together with a valve plateand a discharge valve, between a cylinder block and a housing of arefrigerant compressor under compression, comprising:

an outer sealing portion for sealing an outer circumference of thecompressor against an atmospheric environment therearound;

an inner sealing portion for sealing between a high pressure region anda low pressure region within the compressor, the inner sealing portionbeing provided with at least one predetermined section thereoftrifurcatedly connected to the outer sealing portion; and

a deformable ridge portion formed in each of the outer and inner sealingportions to have the shape of a curved projection with a continuouslyextending apex line, the ridge portion of the predetermined section ofthe inner sealing portion being connected to the ridge portion of theouter sealing portion to form a trifurcated connection in which threeseparate angles “θ” formed between three neighboring apex lines of theconnected ridges are made substantially equal to one another, and anextended and smooth face is provided to contain therein the apex linesof the connected ridge portions of the outer and inner sealing portions.

The above-mentioned combination of the particular angular arrangement ofthe apex lines of the ridge portions and the extended and smooth face ofthe trifurcatedly connected ridge portions of the outer and innersealing portions of the gasket can ensure that the sealing functionexhibited by the gasket for the various sealed portions of thecompressor can be very stable and of a very high quality. Further, thereduction in abrasion of the die for producing the gaskets can bepromoted to increase the productivity of the gaskets by the die.

The above-mentioned extended and smooth face at the trifurcatedconnection of the ridges of the outer and inner sealing portions may beeither a flat face or a smoothly curved face having a radius ofcurvature which is larger than that of the apex line of the ridges ofthe outer and inner sealing portions of the gasket.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, feature and advantages of the presentinvention will be made more apparent from the following description ofpreferred embodiments thereof with refer to the accompanying drawingswherein:

FIG. 1 is a longitudinal cross-sectional view of a refrigerantcompressor, i.e., a swash plate type double-headed piston refrigerantcompressor, in which gaskets according to the present invention areincorporated;

FIG. 2 is a partial enlarged view of a gasket according to an embodimentof the present invention;

FIG. 3 is a partial enlarged view of a gasket according to anotherembodiment of the present invention;

FIG. 4 is a partial perspective view of the gasket of FIG. 2,illustrating a trifurcated connection of the ridges of the gasket;

FIG. 5A is a partial perspective view of the gasket of FIG. 3,illustrating an extended smoothly curved face “T” of the trifurcatedlyconnected ridges of the gasket;

FIG. 5B is a partial perspective view of the gasket of FIGS. 2 and 3,illustrating an extended flat face “S” of the trifurcatedly connectedridges of the gasket;

FIG. 6 is a plan view of a gasket according to the prior art; and

FIG. 7 is a partial perspective view of the gasket of the prior art,illustrating a detailed construction of a portion “A” in FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates a swash plate type refrigerant compressor of the typein which a gasket formed integrally with a valve retainer isincorporated. The swash plate type refrigerant compressor is providedwith axially combined front and rear cylinder blocks 1 and 2 to form aprimary part of the body of the compressor. The front and rear ends ofthe combined cylinder blocks 1 and 2 are closed by front and rearhousings 5 and 6, via front and rear valve plates 3 and 4. The combinedcylinder blocks 1 and 2, the valve plates 3 and 4, and the front andrear housings 5 and 6 are axially connected by a plurality of long screwbolts 7 which are inserted in through-bores 1 a and 2 a bored throughthe combined cylinder blocks 1 and 2. The combined cylinder blocks 1 and2 are provided with a swash plate chamber 8 centrally formed in aconnecting portion thereof. The swash plate chamber 8 receives therein aswash plate 10 which is fixedly mounted on a drive shaft 9 arranged toextend through central bores 1 b and 2 b of the combined cylinder blocks1 and 2. The swash plate 10 rotates in the swash plate chamber 8 whenthe drive shaft 9 rotates.

The combined cylinder blocks 1 and 2 are provided with five axiallyextended cylinder bores 11 arranged around and in parallel with thedrive shaft 9. Radial distances from an axis of rotation of the driveshaft 9 to respective central axes of the five cylinder bores 11 aremade equal. Five double-headed pistons 12 are slidably fitted in thefive cylinder bores 11 to reciprocate therein and, each of the fivedouble-headed pistons 12 is operatively engaged with the swash plate 10via a pair of semi-spherical shoes 13.

The front and rear housings 5 and 6 are provided with front and rearsuction chambers 14 and 15 formed therein in a radially outer regionthereof and front and rear discharge chambers 16 and 17 formed thereinin a radially inner region thereof. The front and rear valve plates 3and 4 are provided with front and rear suction bores 18 and 19 formedtherein through which a refrigerant gas flows before compression fromthe front and rear suction chambers 14 and 15 into respective cylinderbores 11, and front and rear discharge bores 20 and 21 formed thereinfor discharging the refrigerant gas after compression from therespective cylinder bores 11 toward the front and rear dischargechambers 16 and 17.

Suction valves 22 and 23 are interposed between the opposite ends of thecombined cylinder blocks 1 and 2 and the front and rear valve plates 3and 4, and discharge valves 24 and 25 together with gaskets 30 formed tobe integral with valve retainers are interposed between the valve plates3 and 4 and the front and rear housings 5 and 6. The gasket 30 is formedso as to be improved over the gasket 50 of the prior art shown in FIGS.6 and 7.

The description of the gasket 30 arranged on the front and rear sides ofthe combined cylinder blocks 1 and 2 are provided hereinbelow withreference to FIGS. 2 and 3. It should be understood that the gasket 30is made of materials identical with those of the gasket 50. Namely, thegasket 30 is basically made of a metallic plate material and coated withan elastic material such as a rubber material. Further, the gasket 30 isproduced by employing dies and a press machine to be formed in abasically round element similar to the gasket 50 of the prior art, andis also formed to be integral with valve retainers similar to theretainers 53 of the gasket 50.

FIG. 2 illustrates, in an enlarged scale, a characterized portion of thegasket 30 according to a first embodiment of the present invention.Referring to FIG. 2, the gasket 30 is provided with an outer sealingportion 31 adapted to sealing an outer circumference of the refrigerantcompressor when it is incorporated in the compressor, i.e., when it isincorporated between the front or rear housings 5 or 6 and the front orrear valve plate 3 or 4. Thus, the outer sealing portion 31 is formed ina cylindrically extending strip having a radial width necessary forsealing the outer circumference of the refrigerant compressor.

The gasket 30 is also provided with an inner sealing portion 32 adaptedfor sealing between a high pressure region such as the discharge chamber16 or 17 defined in the front or rear housing 5 or 6 and a low pressureregion such as the suction chamber 14 or 15. Thus, the inner sealingportion 32 is arranged radially inside the outer sealing portion 31 andis formed in an annularly extending strip suitable for sealing betweenthe high and low pressure regions. The inner sealing portion 32 hassections connected to the outer sealing portion 31. One of the connectedsections of the inner sealing portion 32 extends radially so as to betrifurcatedly connected to a predetermined position of the outer sealingportion 31, and the other of the connected sections of the inner sealingportion 32 extends so as to be trifurcatedly connected to a differentpredetermined position of the outer sealing portions 31 while passing byone of lug portions 43 in which a through-bore 44 for the insertion ofthe screw bolt 7 is formed.

The outer and inner sealing portions 31 and 32 are provided withcontinuous and deformable ridges 41 and 42, respectively. Each of theridges 41 and 42 is formed as a curved projection having an apex linethereof as shown by solid lines in FIG. 2. A cross-sectional form ofeach of the ridges 41 and 42 is similar to that of the ridge 61 or 62shown in FIG. 5. Nevertheless, the ridges 41 and 42 of the gasket 30 areconnected to one another at the trifurcatedly connecting position of theouter and inner sealing portions 31 and 32 in a manner completelydifferent from the connecting manner of the prior art gasket 50.

In the embodiment of the gasket 30 of FIG. 2, the two trifurcatedconnecting portions of the outer and inner sealing portions 31 and 32corresponding to the portions “A” and “B” of FIG. 6 are different fromeach other. Namely, in the trifurcated connecting position of the outerand inner sealing portions 31 and 32 corresponding to the portion “B” ofFIG. 6, the apex lines of the trifurcatedly connected ridges 41, 41 and42 are arranged to have three separate angles between three neighboringapex lines, which are made substantially equal. Thus, respective anglesare indicated by the same symbol “θ” in FIG. 2.

In accordance with the above-described equi-angular connection of theridges 41, 41 and 42 of the outer and inner sealing portions 31 and 32,the connected three ridges 41, 41 and 42 are arranged to begeometrically balanced to form a balanced trifurcated connection asclearly shown in FIG. 4. Thus, the three-connected ridges exhibit asubstantially equal mechanical rigidity. Therefore, when the gasket 30is held between the valve plate 3 or 4 and the front of rear housing 5or 6 under compression, the three interconnected ridges 41, 41, and 42are elastically deformed in a uniform and stable manner and are capableof exhibiting a good sealing function.

On the other hand, in the trifurcated connecting position of the outerand inner sealing portions 31 and 32 corresponding to the portion “A” ofFIG. 6, the ridges 41, 41, and 42 are connected to one another, so thatthe apex lines of the three ridges 41, 41, and 42 lie in an extendedarea which is formed as a substantially triangular-shape smooth flatface designated by “S”. Namely, as best shown in FIG. 5B, thetriangular-shape flat face is enclosed by three sides formed by thethree apex lines of the three ridges 41, 41, and 42. Therefore, when thegasket 30 is sandwiched between either the front housing 5 and the frontvalve plate 3 or the rear valve plate 4 and the rear housing 6 undercompression, the above-mentioned triangular flat face “S” is in facecontact with a corresponding sealed portion of the front or rear housing5 and 6. Therefore, during the elastic deformation of the connectedportion of the ridges 41, 41 and 42, an unbalanced condition in themechanical rigidity of these ridges is removed by the extended smoothflat face “S” of the gasket 30. As a result, the triangular-shape smoothflat face “S” of the gasket 30 can exhibit a good and stable sealingfunction.

Further, due to the existence of the extended smooth flat face “S” inwhich a part of the apex lines of the ridges 41 and 42 of the gasket 30disappear, when the gasket 30 is produced by employing a die and a pressmachine, a part of an internal shape of the die can be simplified toeliminate any complicated grooves corresponding to the interconnectedapex lines of the ridges 41 and 42. Thus, during the mass production ofthe gaskets 30, abrasion of the die can be appreciably reduced so thatthe productivity of the gasket 30 can be increased.

FIG. 3 illustrates the gasket 30 according to another embodiment of thepresent invention. In the embodiment of FIG. 3, the structure of thetrifurcated connecting position of the outer and inner sealing portions31 and 32 corresponding to the portion “B” of FIG. 6 is different fromthat of the previous embodiment of FIG. 2. In the embodiment of FIG. 3,the interconnected portion of the three ridges 41, 41 and 42 isgeometrically arranged to define three separate but substantially equalangles “θ” between the respective neighboring apex lines of the threeridges 41, 41 and 42. Further, an extended smoothly curved face “T”containing therein the three apex lines of the interconnected portion ofthe three ridges 41, 41 and 42 is formed. As shown in FIG. 5A, theextended smoothly curved face “T” is formed as a convex face curving inthe same direction as the respective ridges and having a radius ofcurvature larger than that of the respective ridges 41 and 42. Thus, forexample, when the gasket 30 is held between the front valve plate 3 andthe front housing 5 under compression, the extended smoothly curved face“T” of the connected portion of the outer and inner sealing portions 31and 32 is elastically deformed, so that not only deformations of thethree respective ridges 41, 41 and 42 at the connected portion thereofare mutually balanced but also the gasket 30 and the sealed portion ofthe refrigerant compressor are maintained in face contact with oneanother. Therefore, a stable and better sealing function of the gasket30 can be obtained. Further, the productivity of the gaskets 30 of theembodiment of FIG. 3 can be very high compared with that of the gasketof the prior art shown in FIGS. 6 and 7, due to the same reason as setforth above with reference to the previous embodiment of FIG. 2. In theembodiment of FIG. 3, the interconnected portion of the ridges of theouter and inner sealing portions 31 and 32 which corresponds to theconnected potion “A” of the gasket 50 of FIG. 6, an extended flat face“S” containing therein the apex lines of the ridges 41, 41 and 42 isformed. The construction of the extended flat face “S” is clearly shownin FIG. 5B. It should be understood that the extended smooth flat face“S” and the extended smoothly curved face “T” of the gasket 30 accordingto the embodiment of FIG. 3 may be replaced with one another asrequired.

From the foregoing description of the preferred embodiments of thepresent invention, it will be understood that, in accordance with thepresent invention, since the gasket for a refrigerant compressor isformed integrally with a valve retainer element and has a circular outerand an annular inner sealing portions which are provided with deformableridges trifurcatedly connected with one another at at least one portionthereof and geometrically arranged to exhibit balanced mechanicalrigidity, the gasket can provide fluid-tight, stable and good sealingfor an outer circumference of the refrigerant compressor as well as aboundary portion between high and low pressure regions within therefrigerant compressor. The trifurcatedly interconnected portion of theridges of the outer and inner sealing portions of the gasket may beformed in an extended smooth flat or curved face containing thereinapexes of the ridges of the outer and inner sealing portions, so thatthe gasket can be in face contact with sealed portions of thecompressor. Thus, the trifurcatedly connected portion of the ridges ofthe outer and inner sealing portions of the gasket according to thepresent invention can exhibit a good sealing function with a highstability.

What we claim is:
 1. A gasket having a surface thereof coated with anelastic membrane and adapted to being interposed, together with a valveplate and a discharge valve, between a cylinder block and a housing of arefrigerant compressor under compression comprising: an outer sealingportion for sealing an outer circumference of the compressor against anatmospheric environment therearound; an inner sealing portion forsealing between a high pressure region and a low pressure region withinthe compressor, said inner sealing portion being provided with at leastone predetermined section thereof trifurcatedly connected to said outersealing portion; and a deformable ridge portion formed in each of saidouter and inner sealing portions including said at least onepredetermined section to have the shape of a curved projection with acontinuously extending apex, said deformable ridge portion of saidpredetermined section of said inner sealing portion being connected tosaid deformable ridge portion of said outer sealing portion to form atrifurcated connection in which an extended and smooth face is providedto contain therein said apexes of said trifurcatedly connecteddeformable ridge portions of said outer and inner sealing portions. 2.The gasket according to claim 1, wherein said extended and smooth faceof said trifurcated connection of said outer and inner sealing portionsis formed in an extended flat face in which said apex lines of saidconnected ridge portions of said outer and inner sealing portions lie.3. The gasket according to claim 2, wherein said extended flat face is asubstantially triangular shape flat face enclosed by three sides formedby said apex lines of said connected ridge portions.
 4. The gasketaccording to claim 1, wherein said extended and smooth face of saidtrifurcated connection of said outer and inner sealing portions isformed in an extended and smooth curved face in which said apex lines ofsaid connected ridge portions of said outer and inner sealing potionslie.
 5. A gasket having a surface thereof coated with an elasticmembrane and adapted to being interposed, together with a valve plateand a discharge valve, between a cylinder block and a housing of arefrigerant compressor under compression comprising: an outer sealingportion for sealing an outer circumference of the compressor between thelow pressure region within the compressor and the atmosphere; an innersealing portion for sealing between a high pressure region and a lowpressure region within the compressor, said inner sealing portion beingprovided with at least one predetermined section thereof trifurcatedlyconnected to said outer sealing portion; and a deformable ridge portionformed in each of said outer and inner sealing portions including saidat least one predetermined section to have the shape of a curvedprojection with a continuously extending apex, said deformable ridgeportion of said predetermined section of said inner sealing portionbeing connected to said deformable ridge portion of said outer sealingportion to form a trifurcated connection in which three separate angles“⊖” formed between three neighboring apex lines of said connecteddeformable ridge portions are made substantially equal to one another,and an extended and smooth face is provided to contain therein said apexlines of said trifurcatedly connected ridge portions of said outer andinner sealing portions.
 6. A gasket having a surface thereof coated withan elastic membrane and adapted for being interposed, together with avalve plate and a discharge valve, between a cylinder block and thehousing of a refrigerated compressor, under compression, comprising: anouter sealing portion for sealing an outer circumference of thecompressor between a low pressure region within the compressor and theatmosphere; an inner sealing portion for sealing between a high pressureregion and the low pressure region within the compressor, said innersealing portion being provided with at least one predetermined sectionthereof trifurcatedly connected to said outer sealing portion in aregion where the gasket seals the high pressure region from theatmosphere; a deformable ridge portion formed in each of said outer andinner sealing portions including said at least one predetermined sectionto have the shape of a curved projection with a continuously extendingapex, said deformable ridge portion of said predetermined section ofsaid inner sealing portion being seamlessly connected to said deformableridge portion of said outer sealing portion to form a trifurcatedlyextending gradually curved connection containing a smoothly curved facewherein the apexes of the connected ridge portions of the outer andinner sealing portions gradually merge; said gasket, when undercompression, elastically deforms uniformly in all regions.